Tube thickener



Dec. u, 1951 E Smm HAL 2,578,636

' TUBE THICKENER Filed March 17, 1948 13 Sheets-Sheet l JNVENTORS lig 5 6. 5mn/1 @L BY 0./2 bcc/nare//a Dec.I ll, 1951 E. G@ SMITH r-:TAL

TUBE THICKENER 13 Sheets-Sheet 5 Filed March 17, 1948 Dec. l1, 1951 E. G. SMITH E'FAL TUBE THICKENER 1.3 Sheets-Sheet 4 Filed March 17, 1948 JNVENTORS Snai/7 g BY 0./1 Coca/wre l/a Dec. 1l, 1951 E. G. sMm-l rs1-A1. 2,578,636

TUBE THICKENER Filed` March 17, 1948 l 13 Sheets-Sheet 6,'

Decll, 1951 E. G. SMITH E1- Ax.

TUBE THICKENER 13 Sheets-Sheet 7 Filed March 17, 1948 MVO,

Dec. 11, 1951 Filed March 17, 1948 E. G. SMITH ETAL TUBE THICKENER 13 Sheets-Sheet 8 De@ 1L 195i E.. G, SMH-H Em, www

TUBE THICKENER Filed March 17, 1948 13 Sheets-Sheet 9 Dec. 1l, 1951 E. G. SMITH ETAL TUBE THICKENER Filed March 17, 1948 13 Sheets-Sheet 1l nw L INVENTO Dec. 1l, 1951 E. G. SMITH ETAL 2,578,636

TUBE THICKENER Filed March 17, 1948 13 Sheets-Sheet 12 1I I I A I 5' il lr 224 223 V U25/ r /9 J F dmv y vf mi i V l l 22/ y f I :I l' M-ifg 295 2% BYOJV. Cocc/na/"g//g Dec. 11, 1951 E. G. SMITH ETAL TUBE THICKENER 13 Sheets-Sheet 13 Filed March 17, 1948 NNN Patented Dec. 11,1951

TUBE THICKENER Edmund G. Smith, Cedar Grove, and Otell M.

Cocchiarella, Newark, N. J., assignors to Equipment Development Co., a corporation of New Jersey Application March 17, 1948, Serial No. 15,396

' 15'c1aimsl (ci. zio- 152i This invention relates to tube. thickeners of the type wherein a tube carrying a filter fabric is immersed in a slurry to be thickened, the filtrate is drawn through the lter fabric and discharged from the tube and the filter cake is removed periodically from the surface of the filter fabric and returned to the slurry.

An object of the invention is to provide a thickener of the above type having novel and improved operating characteristics.

Another object is to provide a thickener of the above type having improved filtering efficiency.

Another object is to provide novel and improved means for removing the filter cake from the lter fabric.

Another object is to provide a novel and improved thickening cycle.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with the present invention a plurality of filter tubes are supported in the slurry from a header which is arranged to be oscillated about a vertical axis so as to cause the tubes to oscillate laterally in the slurry. The lter fabric is Wrapped around spacers which space the same from the surface of the tube to form a suction chamber therebetween and is secured at its side edges so that it is free for independent movement except along the longitudinal line Where the edges are secured.

In the thickening cycle suction is applied to the inside of the tube to draw filtrate through the filter fabric and into the suction chamber between the Vfilter fabric and the tube surface,

thence into the tubes themselves, from which it is removed to the header. At the end of the filtering period the suction is cut olf from the header and liquid is forced back into the tubes to equalize the pressure on the two sides of the filter fabric or to produce a slight excess in pressure on the inside so as to cause the fabric to balloon out away from the spacers. The tubes are then oscillated in the surrounding slurry to dislodge the filter cake which then drops downwardly in the slurry after which the oscillation is stopped and suction is again applied to the tubes and the above cycle is repeated. Inasmuch as the filtering efficiency isthe highest at the beginning of the filtering period, before the filter cake has built up to any substantial extent, it is evident by interrupting the filtering cycle frequently and removing the filter cake, the filter fabric is used to its maximum eiiiciency at' all times. l

Inc., Montclair, `N. J.,

Vspecial timingmeans are used to control accurately the various stages of the operating cycle. The timing means includes adjustable cams which may be set in accordance with the timing required.

Another feature of the present invention involves the method of dislodging the lter cake from the filter fabric. Because the filter fabric is attached rigidly at only one point around its periphery, the remainder of the fabric is free to balloon out and to distort as the tube is moved through the surrounding liquid. During the suction period the fabric is held tightly against the spacing members. During the blow-back period the pressure differential is removed or a slight pressure may be built up within the tube so that the entire fabric is caused to balloon out to a certain extent away from the spacing members. This in itself serves to loosen the filter cake from the outside of the fabric. However, as soon as the fabric is thus ballooned out, the tube is oscillated, thereby forcing the fabric laterally back and forth through the surrounding liquid.l This causes the fabric to balloon out on the trailing side of the tube which of course is rapidly reversed in position as the tubes oscillate. This distortion of the fabric serves to dislodge the filter cake and causes the same to drop off from the outside of the fabric and fall to the bottom of the tank. Hence the fabric is maintained comparatively clean without the use of Scrapers or other instruments which tend to damage the same.

Although the novel features which are characteristic of this invention are pointed out more particularly in the claims, the nature of the invention will be better understood by referring to the following description, taken in connection with the accompanying drawings in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings:

Fig. 1 is a side elevation of the upper portion of a thickening tank embodying the present invention;

Fig. 1a is a side elevation of the lower portion of the tank shown on a smaller scale than Fig. 1;

Fig. 2 is an end elevation thereof;

Fig. 2a is an end elevation of the lower portion of the tank;

Fig. 3 is a top plan view of the thickener;

Fig. 4 is a detail View of the shaking mechanism on a larger scale than Figs. 1 to 3;

Fig. 5 is a vertical section showing the shaking mechanism and cam shaft;

Fig. 6 is a plan view of the cam shaft, driving mechanism and valve operating mechanism;

Fig. 7 is a partial top plan view of the end of the thickener opposite the shaking mechanism;

Fig. 8 is a vertical section taken on the line 8-8 of Fig. 7 showing the thickener tubes and header;

Fig. 9 is a detail view of the valve operating mechanism;

Figs. 10, 11 and 12 are sections taken on the line lill0 of Fig. 6 showing the valves in different positions;

Fig. 13 is a detail view of the cam shaft;

Figs. 14, 15, 16 and 1'7 are sections taken on the line |4-|4, |5-|5, |6|6 and |1-|,1 respectively, of Fig. 13 illustrating the relative positions of the various cams;

Fig. 18 is a detail view of a thickener tube;

Fig. 19 is a section taken on the line |9|9 of Fig, 18 showing the position of the filtering fabric during the filtering period;

Fig. 20 is a horizontal section similar to Fig. 19 showing the position of the lter fabric during the blow-back period.

Figs. 21 and 22 are similar sections showing the position of the filter fabric during the oscillating period; and

Fig. 23 is a diagrammatic View illustrating the complete system.

Referring first to Figs. l, 2 and 3, the thickener is shown as comprising a tank of rectangular section containing. the slurry to be thickened and terminating at the bottom in a cone-shaped hopper 3| having an outlet 32 through which the thickened material may be removed when desired. A plurality of tube filters 33 are supported vertically in the slurry in the tank 30 and are connected to a horizontal manifold 34 having an inlet end 35 adapted to be connected to a source of return liquor and an outlet end 35 adapted to be connected to a source of suction. The tank 30 is provided with inlet connectors 31 through which the slurry is fed to the tank and with an overflow connector 38 for maintaining the liquid at the desired level. A stirrer 42, such as a paddle wheel is mounted on a Vertical shaft 43 which extends upwardly through the tank 33 and is driven by a motor 40 through a reduction gear 41 and a gear train 44 mounted on a bracket 45. The reduction gear 41 is connected t0 the motor 46 by driving belt 4.8.. The driving motor, reductiony gear, and gear train are supported on brackets which in turn are mounted on a horizontal frame 5| carriedby uprights 52 from a supporting frame 53 which is adapted to rest upon suitable supporting beams not shown.

The tube filters 33 are mounted to be oscillated in the manner to be described and are driven by a motor 51 through a rotating cam 58, a rocker arm 59 having a cam follower 6|] and atiming mechanism including cams 6| and 6 2', all of which will be more fully described.

Referring now to Fig. 8,'the tube filters 33 include vertical tubes 65 which are attached at their upper ends to horizontal cylinders 91 carrying sight glasses 63, which in turn are attached to radial tubes |59 carrying flanges 10. The flanges 10.`are connected to iianges 1| by means of bolts 12 carrying clampingnuts 193i and pivoted at 14 to the flanges 1|. The boltsr 12 Vextend through vertical slots in the flanges 10 so that the flanges y10 may be released by 1oosen' 4 ing the nuts 13 and pivoting the bolts 12 about their pivots 14.

The flanges 1| are connected to radial tubes 30 which in turn are connected to a rotatable vertical header 8|. The header 8| is open at the bottom to the manifold 34. It rotates in a stuffing box 32 on the manifold and is sealed to the manifoldV by means of a packing 85. At its upper end the header 8| carries a rod 86 which is supported in bearings 81 and 88 in the frame 5|. The bearing 88 is preferably a thrust bearing adapted to support the weight of the header 9| and tube filters 33.

The shaft 86 is connected to be oscillated by means of a lever 90 which carries at its end a pivoted link 9| (Fig. '7) attached by a collar 32 to a rod93 4which is slidably mounted in bearings 94 (Figs. 1 and 7) and extends the entire length of the tank. At its righthand end, as seen in Figs. 1 and 7, the rod 93 extends through a bearing 35 mounted on the end frame of the machine and is urged to the left by means of a compression spring 96 which extends between the bearing and an adjustable collar 91 secured to the rod 93. An adjustable stop collar 38 is threaded on the end of the rod 93 to limit the movement thereof.

At its lefthand end (Figs. 1, 4 and 6) theA rod 93 carries a yoke |00 which is pinned by a pin |0| to a link |02 which in turn is pinned by a pin |03 to a lever |04 attached to the rocker arm 59 and arranged so that rocking of the arm 59 by means of the cam 58 serves to reciprocate the rod 93 which in turn causes the tube filters 33 to oscillate about the axes of the shafts 86.

Referring to Fig. 6, the cam follower 9|!v is shown as mounted in a yoke |01 carried by the end of the rocker arm F9. The cam 58 is mounted on a shaft |08 journaled in bearings in the frame 5| and driven by gears |09 and |0 through a reduction gear (Fig. 3) which is driven by a belt H2 from the motor 51. The belt ||2 is carriedon sheaves ||3Y and ||4 which constitute a Reeves drive and are adjustable to vary the speed of the cam 5.8. An adjusting wheel |29 of the usual type may be provided for varying the drive ratio of the Reeves drive mechanism.

It will be noted that the spring 95 tends to hold the cam follower 60, in contact with the cam 58 to effect the above mentioned oscillating movement or shaking` ofr the tube filters 33. The motor 51 and associated driving mechanisms are supported on a frame |2| (Fig. 1) carried by the end frame 53.

Referring now to Figs. 4, 5 and 6, the cams 0| and 62 are mounted on a cam shaft |26l which in turn is mounted in suitable bearings |21 in a frame |28.

The cam 6l is adapted to engage a cam follower |29 carriedv on an arm |30 attached to the lever |04 and is adapted, when the cam follower |29 is in contact with the high portion of the cam 6|, to hold the lever |04 to the right as seen in Fig. 4, thereby bringing the cam follower 60 out of engagement with the cam 58 and preventing reciprocation of the rod 93. The cam 6| is driven in counterclockwise direction as seen in Fig. 4 and is adapted, when the cam reaches the position shown in Fig. 4, to permit the follower |29 to drop onto the low portion of the cam 6| so as to release the lever |04 and allow the follower 60 tof engage the constantly driven cam 50 and initiate. the shaking of the tubes.

Inr order to. interrupt the shaking of the tubes after a predetermined controlled period, alever 2 sition the .end

Vrgardless of'the positionvof the lever |3|.

cam follower |38 then rides onto the high portion of the cani 62 -to release the lever |3| from the |3|-is.pivotallymounted abouta-pin |32 and is :.normally held down by a spring |33 which is an- 4.choredtoa-flxedear |34. The end |35 of the flever |3|. is adapted to engage an abutment `|36 attached to the lever |04 to latch the lever ...|04 againstfurther movement when the lever- |3| 1lever|04 is .allowed to oscillate provided the cainfollower` |29 is opposite the low portion of rthe cam 6 I; "However, as soon as the follower |38 reaches the low portion of the cam 62, the spring |33=tends to shift thelever |3| andarm |31 inA a' clockwise. direction. s If atthisinstant the lever .|64 is oscillating and is in a position other than at the vextreme right, the end |35 with the lever |3| .rides-on' the top surface of the abutment |36.

Asfsoon ias the oscillation.` of the lever |04 shifts the lever to its extreme righthand position, the end |35 of the lever |3| rides off of the end of the topsurface of the abutment |36 whereupon the spring |33 pulls the lever |3| downwardly into alignment with the abutment |36 to latch the lever |04 in its extreme righthand position,

. and ,prevent further 'reciprocation of the lever 1:!04' and of thelrod93.

On vcontinued rotation of lcams 6| `and 62, the cam follower |29 rides onto the high portion of the cam 6| vthereby retracting the leverv |04 re- The abutment |36 and conditions the apparatus for *further oscillation when the follower |29l again ridesoif the high portion of the cam 6|.

Itfwillbe noted that the period of oscillation i maybe adjusted by shifting the relative positions of the cams 6| and 62 so as to occupy any de-` sired portion of the complete operating cycle.

Referring to-Figs. 3 and 5, the cam shaft |26 is driven by gears |43 through a reducing gear |44 which in turn is driven through a belt |45 by a, .driving motor |46. The belt |45 engages sheaves |41 and |48 which are adjustable asa Reeves drive by means of an adjusting handle |49 for varying the speed of` rotation of the cam shaft 126.- Y

-Referring to Figs. 5, 6.and 9 the cam shaft |26v also carries cams |53, |54 and |55 which actuatel respectively cam followers |56, |51 and |58 .mounted by brackets |59, |60 and |6| on arms |62; |63 ancl|64 respectively. The arms |62, |63 and |64 are pivoted about a horizontal rod |65 zand.: at their. ends engage pins |66, |61 and |68 (Fig. '10) carried respectively in the lower ends of valve-rodsl69, |10 and |1|. The valve rod |69 is connected to actuate pistons |15 and |16 slid- The rod |69 projects Y beyond the cylinder |11 and is urged upwardly by ingyin a cylinder |11.

. .a compression spring |18 seated between the end of the cylinder |11 and a cap |19 mounted on the -end of the rod |69.V V The cylinder |11 is provided with an outlet port |80 and with an inlet port |8| which are arranged so that communication i therebetweenis established when the piston |15 is in its lowerposition, but is interrupted` when ..1,thepiston`l15 isl elevated. Thehigh portion of ;..th'e cam.|53;engagingthecam follower `|56 serves 6 to hold the valve rod |69 inv its, loweru position. When the follower |56 rides oifofthe high portion of the cam |53, however, the spring |18 shifts the valve rod |69 quickly to its upper position. p

Similarly, the valve rod |10 carries pistons |84 and |85 which are mounted to slide in a cylinder |86 and are held in their upward position by a spring |81. The valve rod |1| carries pistons |88 and |89 which slide in a cylinder |90 and are normally held in their upper position by a spring |9|. The cylinder |86 is provided with an inlet port |92 and an outlet port |93. The cylinder |90 is provided with an inlet port |94 and with an outlet port |95. The outlet port |93 of the cylinder |86 and the inlet port |94 of the cylinder |90 are connected by a pipe |96.

Referring now to Figs. 13 to 17, it will be noted that the cams 6| and 62 are mounted on afconical hub 200 and are clamped againstthe conical surfaces of the hub 200 by means of nuts 20| and 202 respectively. The cam |53 is shown as a split cam comprising parts |53a andv |53b. The part |53a is fixed as by welding to a hub 203. The part |531) engages a conical surface of the hub 203 and is clamped thereto by means of a clamping nut 204. The cam |54 engages the conical surface of a hub 205 and is clamped .by a clamping nut 206. The cam engages the conical surface of a hub 2 01 and is clamped by a clamping nut 208. I'he various hubs are fixed on the shaft |26 by means of suitable clamping screws. The arrangement is such that the relative positions of the various cams 6|, 62, |531), |54 and |55 may all be adjusted with respect to the fixed cam |53a which serves as a reference point. The split cam |53, as indicated in Fig. l5, permits adjustment of the actual dwell of the cam follower in the low portion of the cam.

Referring to Figs. 18 and 19, at its lower end the tube 66 is shown as carrying a lter tube 2 |4 which may be welded thereto and is provided at its lower end with a plurality of slots 2|5 and carries on its external surface a plurality of spaced radial fins 2|6 which constitute spacing members. A backing fabric such as a wire screen 2|1 is wrappedaround the peripheral surfaces of the ns 2|6 and is secured at its side edges to a vertical bar 2|8 by suitable means such as solder. If made of non-metallic material its side edges may be overlapped and secured by means ofa strip gasket 2|9, a clamping strip 220, and

A filter fabric 222 of suitable lter material, such as filter cloth of the type described in the copending application of Edmund G. Smith, Serial No. "106,994, led October 3l, i946 for Filter Cloth, now abandoned, is wrapped around the backing fabric 2|1 and its side edges are secured between the gasket 2 I9 and the bar l 2|8. The side edges may be overlapped under the strip gasket 2|9. The upper ends of the fabrics 2|1 and 222 may be folded over the tops of the fins 2 |6 and secured by a gasket 223 and a clamping ring 224 engaged by a clamping nut 225. The lower ends of the fabrics may be folded under the lower ends of the ns 2 |6 and clamped against a bottom plate 226 of the tube by means `of a gasket 221, clamping ring 228, and nut 229 threaded on a bolt 230 which is attached to the bottom plate 22-6. The plate 226 may be welded 'to the bottom of the tubevto serve as bottom closure therefor. A vent 23| is provided at the 'upper part of the tube to prevent an air lock from forming in the filtrate space during the blow-back periods.

111; Referring .now to F1a. 23. the slurryfito. be

vvthichene'c1-is{feci-rioni amper-35 into @slurry tank 23's from which it ispufhped Hymeahsjor a-puihp 231 through Aa pipe 23|wtothe inlet connectors f3? of the thickenertank so. Any overflow-from the thickener tank is removed from the overflow "conhector 3a through fa 'pipe 239 and returned to the 'slurry tank :235.

The outlet eh'd oi thef'n'an-ifold 3.4 4isI connected by fa pipe 240 'to a control valve 2 4|, thence by a pipe 2'42 to a vac'uumreceiyer'243 which in turn is v4connecteol to T a vacuum vfp'urnp 244 by 'r'iie'ans of a pipe 233. The 'control 'valveydl is ofV the jquikraeting diaphragm type having a diaphragm 245 lcor'inected to be actuatedv by suction supplied by a l'suction foi-'peA 2te so "that/the vaive- -2ee r,

v'is lopened only when suction is 'applied 'to the diaphragm 245 through the'pipe 245 by loperation f the pis-170115115 and -IVTB in cylinder |11. T he vacuum v"receiver 243 is connected by a pi-'pe 241 to a filtrate '-pih'p 2'48 -which in turn is'eOn-i /ncted by a pipe2s`4'9 to feed the filtrate t'o an air separating tank 250 which is of 'suf-cierit "size to permit detentionof the nitrate so that entrained air will separate `vand the liquor carriedito tank 253 b'y 'pipe 252 'win 'be free 'from entraine@ The overflow from-the tank 250 is taken by an overflow pipe 251-. The tank 250 is connected' by a pipe -252 to -a head tank 253, the love'rfiow of 'which/is bonneoted by a pipe 254 to the overjnow fpifpe 25|. The head tank 2te reeds hy a pipe 255 t'o a rtuiih-liqui'd control valve 255 vwhich is of the `'quickieactir'ig iaouuvr'n-operated type hav-- fing a diaphragm Controlled by the 'Suction A'in aupi'pe 258 underthe control "ofpistons |84 and |85 in cylinder |86 and pistons |88 and |83 lin cylinder |90., THi/alv 2 56 'in tllln iS-'ollliected by a pipe 25`9't'o the inlet end Y35 of the nianifold 34.

The vacuum pipe 245 is connected tofthejport V|53!) of the Cylinder |11. Theyac'uujn pipe-'258 is connected to the port '|95 o f the cylindt-jirA |90. The port |92 of the `cylinder n|56 and the port |8| of the cylinder |11 fare A `co'rinectedV by a pipe 260 to Athe 4vacuum receiver -24'3 ftov supply vacuum to the respective cylinders. The 'return Vliquifd lcon- `tering, second blow-back, third'shakig 'the lter inaayexeessfdvernowmg through the :pipe '239.

"Baring the lterling'cycle vthe valve 256 is closed and the valve 24| 'opene'dfand suction-is applied from the vacuum receiver through the ivalve '24| tothe 'manifold 34, thence t'o the various tube This suction Vcauses filtrate to be drawn into the tubes through the lter cloth 222,

*whence it flows downwardly through the space Abei'lween "the fins 2|'6 and through the slots 2|5 ir'ito the tube 2'|4, whence it is drawn by suction `through the tube 66 to the manifold 34 and into .fso that the liquor returned to the thickener, for

tube to remove the filter cake. Thecyc'le maybe of any length desired depending u'porrthe nature of the material being tlfiicliened.l A cycle of `40 seconds may be used incertaininstans which case suction may be applied duringtlfie `filtering step for 34 seconds of "the cycle, blow-back;finay be applied for faboiitll/z seconds, and shaking "may involve 21/2 seconds, the 4re'rrfainder 'of the time representingfthe :period of-eh'an'gig from one step to the next, Theftubes maybe oscilla-ted at a rate Of`60 oscillations pel.Trilliumy I`1 which 'v-ent WO `'(16111''pleteosoillatil'i'sl will take lplc `n the 2 1/2 second vos'cillat'ion period.

Referring to Fig. 23, assume "thaitthe slurry tank 23s is maintained fron or the slurry and the feed pump 231 is operating 'toinaintaid-the thicki'f `tahk'il jfull'bf the Slry 'fr''tlibkencreating ahead to force liquor back into the tubes may lose this entrained air or gas, the liquor lmay 'have a fspecic gravity so 'low that it can not create'the required head unless the head tank 253 is `raised beyond a practical height. If the head tank is raised too high, excessive pressure is 'developed on the cloth -should the head tank ysuddenly receive -heavy liquor, as when v*starting up. The cloth may thenv be lstretched and the volu'rneof return liquor required increased apprelciab1y.

Atv the end of the predetermined time, 'so `selected thata filter cake has been built up on the filter cloth 222, the valve 24| is closed by opera- .tion of the 'cam |53 and the valve 256vopen`ed by operation of the cam |54. When the valve 256 vis opened, vliquid ows from the head tank v253 under the h eadfof 'the Iliquid in that tank through the pipe 255 'into 'the 'manifold '34 and thence to the interior 'of the various tubes 33. The pipe 255 and manifold 34 are of large fdiameter so that the liquidsurges back and fills the variousV tubes 'a minimum time. For example, the vliquid may ilow at the -rate of 20 :gallons per second. inasmuch -as the tubes are already -full of the filtrate only a relatively' small quantity of return `liquid-'is required for yfilling the system, breaking fthe-suction on lthe tubes, and feeding back "to balloon out the fabric. The valve 256 must have suicient capacity to pass the liquid at this -maximum-rate and mustbe capable 'of closing 'sub- 'stantially instantaneously when sufficient liquid has passed therethrough. A quick-closing valve of the type referred to :in our oo-pendrig-application Serial No. v8146, above-identified lis suitable for this purpose.

The liquid is fed vback Vuntil the/pressure within and without'th'e tubes 33 lis equalized and a slight excess of pressu're is developed within the tubes. This results in causing the 'filter fabric v222 Yto balloon Vout away from the backing screen 2|1 'as indicated in yFig. 20. It 'will 'be noted that as the fabric is 'securedo'nly 'at one point, it is free to lballoon 'out Aarci-ind practically the entiresurface 'of the tube. In this way'the fabric 'is stretched and the lter cake is loosened. The valve-256 is now closed by operatioh of Athe cam |55 andthe tubes are o's'cillated. The 'oscillation'of the (tubes causes them toA niove `1irst in 4one direction and then the other through 'the slurry. which in "causes the loose fabricto balloon out/in back 9 of the tubes as indicated in Figs. 21 and 22, rst on one side and then on the other as the tubes are moved in alternate directions. This ballooning out of the fabric further distorts the cake and causes the same to fall from the surface thereof into the hopper at the bottom of the slurry tank.

Usually two complete oscillations are suiiicient for this purpose.

After the predetermined period of oscillation, the tubes are again brought to rest and the valve 24| is again opened by operation of the cam |53 to begin the ltering operation of the next cycle. This cycle of operation is repeated in controlled sequence for each rotation of the cam shaft |26.

In the discharge period some liquor passes through the filter cloth as it changes from a circular to an elliptical shape. The use of a cloudy liquor in ballooning out the cloth is objectionable since it sometimes leaves a deposit of solids on the inside of the cloth and retards the flow of liquor through the cloth and interferes with discharge of the filter cake.

The internal volume of the tube 2 |4, the cylinder 61, the pipe line 69 and pipe line 80 is so designed that their combined capacity is greater than the amount of liquor required to balloon out the cloth and to provide for any amount allowed to pass through the cloth 222 during the discharge operation. In this way, if the filter cloth on one or more tubes should develop a hole, producing cloudy ltrate in the horizontal manifold 34, there will always be suflicient clear filtrate in the individual tube and pipe line to perform the desired function, without ever getting any solids back against the inside of the the position shown in Fig. 15 the cam |53a lis` about to reach the drop-off point. In this position all of the cam followers |56 to |58 are riding on the high portions of the cam as indicated in Fig. 9 and all of the valves are held in their downward position as indicated in Fig. 10. In this position suction is applied to the pipe 246 through the cylinder |11 and suction is cut-off from the pipe |96 and hence from the pipe 258 by the piston |85 in the cylinder |86. Suction isr thus applied to the diaphragm 245 of the valve 24| to hold that valve open, but is cut off from the diaphragm 251 of the valve 256. Hence that valve is closed. The followers |29 and |38 are also engaging the high points on their respective cams so that the lever |04 is held to the right as shown in Fig. 4, the follower 60 is out of contact with the cam 58 and the tubes stationary. This position of the cams represents the end of the filtering period. Slight further movement of the cams causes the follower |56 to drop off oi the high portion of the cam I 53a, thereby raising the piston |15 of the cylinder |11 to the position shown in Fig. 11 and cutting off the suction to the pipe 246. This closes the valve 24| and endsl the filtering stage of the cycle. Almost immediately thereafter the cam follower |51 rides oif` of the high portion of the cam |54 to raise the piston |85 which establishes communication between the suction port |92 and the pipe |96,

10 thence through the cylinder |90 to the suction port |05 to apply suction to the pipe 258 and open the valve 256. The return liquid thence flows rapidly from the head tank 253 into the manifold 34. This position of the valves is shown in Fig. 11. When the cams have rotated a slight further amount as indicated by the angle of the line O-O in Fig. 17, the follower |58 rides off of the high portion of the cam |55 to thereby elevate the piston |88 of the cylinder |96 to the position shown in Fig. 12. This cuts off the suction to the outlet port |95 and cuts off the suction to the pipe 258 thereby closing the valve 256 and ending the blow-back period. It is thus evident that the extent of the blow-back period depends upoii the relative angular settings of the cams |54 andk|55 and may be adjusted as desired. Furthermore, by using the drop oil portion of each cam for initiating and stopping the blow-back period respectively, the valve 256 may be opened and closed substantially instantaneously. Hence the quantity of return liquid may be accurately controlled.

Upon further rotation of the various cams, the follower |20 drops ofi of the high portion of the cam 6|, the follower |38 still engaging the high portion of the cam 62. This releases the lever |04 Yand permitsthe follower 60 to engage the cam 58. Rapid rotation of the cam 58 causes the arm 59 and the rod 03 to reciprocate rapidly, which in turn oscillates the shaft 86 and causes the tubes 33 to shake or oscillate in the tank 30. This continues until further rotation of the cams allows the follower |38 to ride off of the high portion of the cam 62, thereby bringing lthe end- |35 of the lever |3| into alignment with the abutment |36 and stopping the oscillation f the tubes as above described. In practice, the cams may be so timed that only two or three complete oscillations take place. This completes the operating cycle In order to set up the next cycle the follower |56 rst rides up on the high portion of the cam |53, again applying suction to the line 246 to open the valve 24|. As the respective followers |51 and |58 are caused to ride up on the high portions of the cams |54 and |55, the valve |86 is first closed by lowering of the piston and the valve is then opened by lowering of the piston |88, thereby restoring the parts to the condition shown in Fig. 10.

While the system has been described as so timed that its blow-back period precedes the shaking, it is obvious that the cams may be so set that the shaking or oscillating of the tubes takes place during the blow-back if desired. While the blow-back assists in loosening theY filter cake.it is applicants belief that the' filter cake is principally removed due to the distortion of the fabric itself during the shaking period and that the principal object of the blow-back is to relieve the suction on the filter cake before and during the shaking of the tubes. I

Although a specific embodiment of the invention has been shown for purposes of illustration.' it is to be understood that the'invention is capable of various uses and that changes andadaptations may be made therein as will be readily apparent to a person skilled in the art.l The invention is only to be restricted in accordance with the scope of the following claims. A

What is claimed is:r I

1`. The method of removing a filter cake/from a tube lter having a tubular surface composed of a yiie'xibleiilter material which comprises, at

the .end yof the filter period, returning liquid to theinterior of 'said tubefilter to cause the material' to 'balloon out, then rapdily oscillating said filter laterally with respect to its axis in said slurry to cause the filter material to balloon out, first in one direction andthen in the other on its trailing kside so as to dislodge the filtery cake therefrom. i

2. A method of operating a tube thickener comprising a tube .carrying a layer of filter material thereon, which comprises first applying suction to .said tube to draw the filtrate through said material and cause a filter cake to deposit on the surface thereof, then breaking said suction and applying Areturn liquid to said tube to cause, vsaid material to balloon out away from the surface of said tube, then interrupting the supply'of return liquid andoscillating said tube laterally withrespect to its axis in the surround'- ing slurry for a predetermined period of time so as to cause the Vfilter material to balloon out on the trailing side ofthe moving tube first on rone side and then on the other side as ythe tube -oscillates for dislodging the filter fcake therefrom.

3. A tube thickener comprising a tank for a slurry to be thickened, a tube 'carrying a fabric filter material around its periphery immersed in said slurry,said fabric :being free of said tube to. :balloon out therefroml aroundv a substantial portionof its periphery', a suction pipe connected to said tube for applying suction to draw filtrate through said .filter material and to cause a filter .cake to deposit thereon. Ya suction, controlfvalve connected in said suction pipe to control the suction :of saidtube. a. return pipe carrying return liquid connected to supply return liquid to said tube, a return liquid valve .connected in said return pipe to control the flow of the return liquid from said return pipe to said tube, a driving vmember connected to oscillate said tube laterally with respect'to its axis in said-slurry to cause vthef'ilter material to balloon out on its trailing side, first on one side, of theV tube and then on the other Aas the tube is oscillated, and timed means having means operatingl automatically and in timed sequence andconnected'to first open lsaid suction control valve for filtering., then to close said suction control valve andy to open saidY return liquid valve for a predetermined accurately timed pe- .f

riod to supply return liquid to saidv tube, then actuate `'said' driving member to oscillate said tube so as to dislodge the-filter cake therefrom, and then repeat said operations cyclically.

4. A `tube thickener, as set forth in claim 3, in which saidI tube is disposed vertically in said' slurry andV said oscillating meansl is connected to oscillate said tube horizontally therein'.

A tube thickener, as setl forth in claim 3I including a plurality of said tubes, a manifold. mounted to rotate about a vertical axis, a plu-- rality 0ftubular arms extending radially outward therefrom,A onefof said tubescarrying lter material being mounted on each of said arms and extending vertically in said slurrry, said Oscillating means being connected to oscillateV 'said manifold about said vertical axis to cause lateral oscillation of said tubes insaid slurry.

61 A tube thickener, as set forth in claim 3* in which pressure responsive devices are connected to actua-te said suction control valve and said return liquid valve and said timed means includes connected means to control the pressure supplied to said devices.

7.v A tube thickener, as set forth .in claim 3,

infwhichsaid oscillating means comprises a rotating cam, a cam follower is arranged to engage .'an'd vvbe actuated by said cam and is connected tooscillate said tube, and a holding cam is :arranged to hold said follower out of engagement `with. said rotating cam to interrupt the oscillation of said tube during selected periods.

8. In a tube thickener, as set forth in claim 7, latch means connected to hold said cam follower ,out of engagement with said holding cam, andan additional cam rotating With the holdingcamrarranged to release'said latch means.

9. A .tube thiokener comprising a tank for a slurry .to be thickened, a tube carrying a fabric filter .material around its periphery immersed in said slurry, said fabric being free of said tube to balloon out therefrom around a substantial p0rton of vits periphery, a suction pipe connected to said tube for Vapplying suction to draw filtrate through said Afilter'material andr to cause a filter cake yto deposit thereon, a suction control valve connected in said suctionpipeto control the suction-of said tube, a return pipe carrying return liquid connected to` supply return liquid to said tube, a return vliquid valve connected in said return `pipe-tocontrol the flow of the return liquid from saidreturn pipeI to said tube, a driving member connected to oscillate said tube laterally with respect to its axis in said slurry to cause the filter material tol balloon out on its trailing side, first on one -sidefof the 'tubeand then on the other as the tube Vis oscillated, and timed means having means Operating `autornatically and in timed sequence and connected` to first onen said suction control valvefor filtering-then 'to close said suction control valve and to, open said return liquid valve for a predetermined accurately timed period to supply return liquid to said tube, then actuate said driving member'to oscillate said tube so as to dislodge the filter cake therefrom, and then repeat said operations eyclically, vacuum responsive means connected to open said return Aliquid valve in response to suctionandv to close said return liquid valve-when said -suction is released, a suction line connected to actuate said vacuum responsive means, and valve, means in said suction line comprising a pair of cylinders each having inlet and outlet ports and a slidable piston therein adapted to establish or break communication between the respective inletand outlet ports, said ports 'being connected to connect vsaid cylinders in series in said suction line and so arranged that actuation of one piston opens the suction line to apply suction to said vacuum responsive means for opening said return valve and 'subsequent actuation of the second piston releases the suction on said vacuum responsive means for closing said return valve.

10. In a tube thickener, as set forth in claim 9, rotaryv cams having followers connected to actuate said pistons, each of said cams having a sharp drop-offportion adapted to produce rapid actuation of the responsive-pistons.y

1I. Ina tube thickener, as set forth in claim 10, means for adjusting the relative timing of said cams for thereby controlling the open period of said return valve.

12. A tube thickener, comprising a tank for a slurry to be thickened, a tube carrying a fabric filter material around its periphery immersed in said slurry, said fabric being free of said tubetto balloon out therefrom around a substantial portion'ofi its periphery, a suction pipe connected to said tube. for applying suction to said tube to draw filtrate through said filter material and to deposit a filterv cake thereon, a return pipe carrying return liquid connected to supply return liquid to said tube to loosen the lter cake, means to oscillate said tube laterally in a direction substantially normal to its axis in said slurry to cause the iilter material to balloon out on its trailing side, rst on one side of the tube and then on the other as the tube is oscillated to dislodge said cake, and timed means having means operating automatically and in timed sequence and connected to control the suction period for filtering,

the oW of return liquid to said tube, and the period of oscillating said tube.

13. In a tube thickener, a tank for a slurry to be thickened, a filter tube disposed vertically in said tank and carrying fabric filter ni'aterial around its periphery, said fabric being free of said tube to balloon out therefrom around a substantial portion of its periphery, means to oscillate said tube laterally in a direction substantially normal to its axis in saidv tank to cause the lter material to balloon out on its trailing side, rst on one side of the tube and then on the other as the tube is oscillated, and timed means to control said oscillation. v

14. In a tube thickener, a tank for a slurry to be thickened, a filter tube disposed vertically in said tank and carrying a filter fabric around its periphery, a driving member connected to oscillate said tube laterally in a direction substantially normal to its axis in said tank to cause the fabric to balloon out on its trailing side, first on one side of the tube and then on the other as the tube is oscillated, timed means to control said oscillation, and attaching members attaching said fabric to said tube intermediate its ends only along a longitudinal line lying in a diametric plane of the tube extending in the direction of oscillation so 14 that the fabric is free to balloon out on both sides of said longitudinal line.

15. The method of thickening a slurry which comprises immersing therein a tube carrying a lter material around its periphery, applying suction to the interior of said filter for drawing ltrate therethrough and depositing a lter cake thereon, breaking said suction and supplying return liquid to said iilter for equalizing the pressure therein, and rapidly oscillating said lter laterally with respect to its axis in said slurry to cause the lter material to balloon out on its trailing side, iirst on one side of the tube and then on the other as the tube is oscillated to dislodge the lter cake therefrom.

EDMUND G. SMITH. OTELL M. COCCHIARELLA.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 

